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(a) Balcoracania dailyi (~10mm), (b) Paradoxides gracilis (110mm), (c) Olenellus (~20mm); (d) Acadoparadoxides briaerus (300mm) (e) Isotelus rex (720mm), (f) Parabarrandia bohemica (120mm), (g) Pricyclopyge binodosa binodosa (20mm), (h) Cybantyx anaglyptos (50mm), (i) Aulacopleura konincki (20mm); (j) Leonaspis (10mm), (k) Erbenochile erbeni (50mm), (l) Kathwaia capitorosa (~30mm), (m) Ditomopyge (~30mm). During moulting, the exoskeleton broke across joints, or sutures, between the segments, such as the facial sutures, which join the free cheeks to the rest of the cephalon (Fig. After moulting, the individual took on water to swell its body size before growing a new exoskeleton.

Sources: (a) Paterson and Edgecombe, 2006; (c,j) Levi-Setti, 1993; (e) Rudkin et al., 2003; (g) Horný & Bastl, 1970; (h) Whittington, 1997; (i) (k) Chatterton and Gibb, 2010; (l) Owen, 2003; (m) Moulting was an important part of the trilobite life cycle.

Over the course of their long history — which dates back to near the beginning of the Cambrian period, around 520 million years ago — they have inhabited a wide range of marine environments, from reefs to abyssal depths. Trilobites show excellent examples of convergent evolution, whereby morphological characters such as these are independently evolved in unrelated species e.g. An interesting example of convergence is Aulacopleura konincki (Fig 1.

Derartige erdgeschichtliche Dokumente können sowohl körperliche Überreste von Lebewesen (Körperfossilien) sein als auch Zeugnisse ihrer Aktivität (Spurenfossilien).

Zum Beispiel werden auch versteinerte Trittsiegel und Exkremente (Koprolithe) zu den Fossilien gezählt.

The earliest scientific report of a trilobite fossil was by Reverend Edward Lhwyd in 1698. In the early stages of development, this process was used to increase the number of thoracic segments, as well as the overall size of the animal. The world’s biggest trilobite—Isotelus rex new species from the Upper Ordovician of northern Manitoba, Canada.

This specimen was collected near Llandeilo in South Wales, and was originally described by Lhwyd as “some kind of flat fish” (Fig. Later, following more and more fossil discoveries, trilobites were recognized as arthropods, more closely related to crabs, spiders and lobsters than to fish. Trilobite development can be broadly divided into three main stages: protaspid, meraspid and holaspid (Fig. The protaspid and meraspid phases involve moulting followed by an increase in segment number (anamorphic growth pattern).

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